Mass producing super-thin films that can 'squeeze' electricity

Today, we might take it for granted that mobile-phone cameras, desktop printers, medical equipment, automobile parts and other everyday items will continue to get smaller, lighter and more reliable.These enhancements seem so natural and gradual that we might not even realise it on a day-to-day basis.

However, many technological advances are needed to improve and miniaturise such devices. One such advance is the growing use of a type of thin material known as “piezoelectric” film. The European Union (EU)-funded project PIEZOVOLUME focused on speeding the production of this material. The research team worked to develop high-volume production tools and methods that are expected to help make the high-tech devices and systems of the future faster, lighter and more efficient.

Up to 100 times thinner than a piece of office paper, these ceramic “piezoelectric” films have the remarkable ability to either generate electricity when squeezed, or to move when subjected to electricity. Translated from the original Greek, in fact, piezoelectric means “pressure electricity.”

The thin films, as delicate as they may be, are an essential component in a growing number of medical, communications, aerospace and consumer products – from ultrasound machines and computer disc drives, to automobile airbags and miniature pumps, to disposable blood-pressure sensors and even machines that could scavenge energy from vibrations.

Despite the critical importance of piezoelectric thin film, Europe has lacked the ability to mass-produce it on an industrial scale. This has held back the competitiveness of industries that rely on the material. “By mass-producing piezoelectric films, we can ensure that a whole range of electronic devices become smarter than they are now,” says PIEZOVOLUME coordinator Frode Tyholdt of the Norwegian research organisation SINTEF. “Europe has a chance to lead in this field.”

Tyholdt notes that an endless range of devices will need to become smaller, use less power, perform better, and be easier to manufacture. Piezoelectric microsystems can help achieve this goal. “There is a limit to how small traditionally manufactured parts can be,” explains Tyholdt. "Piezoelectric microsystems can solve this problem, and they can also let us do things we could not do before.”

As futuristic as they sound, piezoelectric materials are not a recent innovation. They were first used in sonar devices in World War II to detect enemy submarines and underwater mines. They are still used by boats, including in fishing crafts to find schools of fish. Piezoelectric microsystems now have countless uses – to make auto-focus camera lenses smaller and faster, and to miniaturise the ink dots produced by computer printers. “Industries are constantly working to make their products smaller and smaller,” says Tyholdt. “This is where piezoelectric film can come in.”

Because piezoelectric materials can generate electricity when shaken, systems in the future could generate their own electricity by harvesting it from nearby vibrations. This would be ideal for equipment or machinery for which changing batteries is difficult, such as in remote locations.

Commercial success resulting from the PIEZOVOLUME project has already been recorded – and this has been particularly beneficial for small- and medium-sized enterprises (SMEs). Several companies are using the new types of tools developed by Tyholdt’s team, and others have already begun to incorporate these films into their products, including a manufacturer of auto-focus camera lenses for mobile phones.

Additionally, the first competence centre with the capability to prototype piezoelectric microsystems in Europe has been established. “We are making a lot of progress,” says Tyholdt. “These advances are expected to speed the time for new products to reach the market, open new horizons for SMEs, and ease the introduction of piezoelectric materials into new industries,” concludes Tyholdt.